From: Berkant Koc <[email protected]> Sent: Tuesday, May 19, 2026 1:08 PM > > A SYNTHVID_RESOLUTION_RESPONSE with resolution_count > 64 walks past > the supported_resolution[SYNTHVID_MAX_RESOLUTION_COUNT] array in the > parse loop. Bound resolution_count against the array size, folded > into the existing zero-check. > > When the WIN10 resolution probe fails, the caller in > hyperv_connect_vsp() left hv->screen_*_max / preferred_* unpopulated, > which sets mode_config.max_width / max_height to 0 and makes > drm_internal_framebuffer_create() reject every userspace framebuffer > with -EINVAL. The pre-WIN10 branch had the same gap for > preferred_width / preferred_height. Use a single post-probe fallback > guarded by screen_width_max == 0 so both paths converge on the WIN8 > defaults. > > Signed-off-by: Berkant Koc <[email protected]> > Assisted-by: Claude:claude-opus-4-7 berkoc-pipeline > Fixes: 76c56a5affeb ("drm/hyperv: Add DRM driver for hyperv synthetic video > device") > Cc: [email protected] # 5.14+ > Reviewed-by: Michael Kelley <[email protected]>
I ran a basic smoke-test on my local Hyper-V instance. I can confirm that no error messages or failure were generated in the "good" case where the resolution_count from Hyper-V is valid. I did not simulate a bogus resolution_count and ensure it is detected. Tested-by: Michael Kelley <[email protected]> > --- > drivers/gpu/drm/hyperv/hyperv_drm_proto.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c > b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c > index 051ecc526..c3d0ff229 100644 > --- a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c > +++ b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c > @@ -391,8 +391,11 @@ static int hyperv_get_supported_resolution(struct > hv_device *hdev) > return -ETIMEDOUT; > } > > - if (msg->resolution_resp.resolution_count == 0) { > - drm_err(dev, "No supported resolutions\n"); > + if (msg->resolution_resp.resolution_count == 0 || > + msg->resolution_resp.resolution_count > > + SYNTHVID_MAX_RESOLUTION_COUNT) { > + drm_err(dev, "Invalid resolution count: %d\n", > + msg->resolution_resp.resolution_count); > return -ENODEV; > } > > @@ -508,9 +511,13 @@ int hyperv_connect_vsp(struct hv_device *hdev) > ret = hyperv_get_supported_resolution(hdev); > if (ret) > drm_err(dev, "Failed to get supported resolution from > host, use default\n"); > - } else { > + } > + > + if (!hv->screen_width_max) { > hv->screen_width_max = SYNTHVID_WIDTH_WIN8; > hv->screen_height_max = SYNTHVID_HEIGHT_WIN8; > + hv->preferred_width = SYNTHVID_WIDTH_WIN8; > + hv->preferred_height = SYNTHVID_HEIGHT_WIN8; > } > > hv->mmio_megabytes = hdev->channel->offermsg.offer.mmio_megabytes; > -- > 2.47.3 >
